[Nottingham] Very slow dd if=/dev/random

Martin nottingham at mailman.lug.org.uk
Tue Jul 29 09:59:00 2003

Ben Blackburne wrote:
> On Tue, 2003-07-29 at 09:28, Martin wrote:
>>Meanwhile, I tried:
>>dd if=/dev/random of=/dev/hdg bs=1M
> <snip>
>>So why doesn't this work at 10's MBytes a second?
> Just a guess really - /dev/random requires generating random numbers
> which I think are "truly" random - they come from an entropy store
> generated by mouse movements, network activity etc.
> So this probably takes a while to generate.

Now trying /dev/urandom and dd is taking 60-ish% cpu so it may well be 
doing something!

Thanks folks,

Martin Lomas